Well firstly I have a son who unlike all of the others ( who are pigs) doesn't eat a damned thing, so it may or may not be his mothers alleged eating problems that are causing it. Is he clinically underweight and ill or just a kid with no interest or appetite as my son? Sometimes that would be hard to judge unless he's seen a Dr about it. His Mum may not welcome your well meaning attempts to find a solution to the percieved problem and I'd be wary about trying to get a psychologist involved unless absolutely necessary as it will add to his sense that there is something wrong with him and reinfoce whatever bullying is taking place.It's first and foremost the bullying that needs addressing, after that his mother can liase, and via his GP,if he thinks he needs it, get a referral, but it would be unusual for a 10 year old male to be anorexic for example and he and his mum may resent the implication that he is so I'd tread carefully if I were you as your attempts to help might be misconstrued and viewed as critisism. Hope everything works out ok.